1. Field
The present disclosure relates to methods of operating a power device to reduce current collapse that occurs by trapping electrons of a channel in a semiconductor layer when the power device is transformed from an off-state to an on-state.
2. Description of Related Art
A high electron mobility transistor (HEMT) is one type of power device. The HEMT includes compound semiconductors having polarizabilities different from each other, and a 2-dimensional electron gas (2DEG) that is used as a carrier is formed in a channel layer. In an HEMT, when turning off the HEMT, a high voltage may be applied to a drain electrode, and thus, electrons from a gate electrode may be trapped in a channel supply layer near the drain electrode or a surface of the channel supply layer near the drain electrode. Also, hot electrons of a channel may be trapped in the channel supply layer.
When a HEMT is turned from an off-state to an on-state, the trapped electrons may be unable to escape from where they are trapped, and thus, a portion of regions of the channel may be depleted. As a result, on-resistance may increase, and accordingly, current collapse may occur. Due to current collapse, resistance in the HEMT may increase, heat generation may increase, and degradation of the HEMT may be accelerated.
In order to reduce the current collapse, using a field plate or forming of a protective layer on the gate electrode has been attempted.